In 3GPP (3rd Generation Partnership Project), which is one of standard establishment projects of a communication network, there have been examined Evolved Universal Terrestrial Radio Access (hereinafter referred to as EUTRA), which is an evolved third generation mobile communication system, and Advanced EUTRA (also called LTE-Advanced), which is further evolved EUTRA.
In Advanced EUTRA, Carrier Aggregation has been proposed as a technology with which higher-speed data transmission can be achieved while maintaining compatibility with EUTRA (Chapter 5 in Non-Patent Document 1). Carrier aggregation is a technology with which a transmission apparatus transmits data to a reception apparatus using a plurality of different frequency bands (also called component carriers, carrier components, or element carriers), and with which broadband communication is achieved by virtually considering a plurality of different frequency bands as one frequency band.
A mobile station apparatus in a connected state (Connected Mode) in a communication system needs to perform a handover procedure in order to measure a reception quality of a signal transmitted from a base station apparatus and to sequentially switch communication to a base station apparatus with better quality than the currently connected base station apparatus. Therefore, a mobile station apparatus of Advanced EUTRA (hereinafter simply referred to as a mobile station apparatus) needs to measure reception qualities of a plurality of component carriers and to compare the reception qualities, respectively for handover. Handover is started by an instruction of the base station apparatus to which satisfaction of an event condition has been reported when the base station apparatus previously informs the mobile station apparatus of a predetermined event condition (Measurement Reporting Event (event trigger condition or measurement report condition)) and a parameter (Event Triggered Reporting Criteria (event trigger criteria)) used for the event condition, and the mobile station apparatus determines whether or not the informed event condition is satisfied (event determination) and determines that the event condition is satisfied as a result of the event determination (for example, Section 10. 1. 2 in Non-Patent Document 2). It has been examined that event determination is performed for each carrier component as described in Non-Patent Document 3.